Question

Cavity of the gastrula is
a. Coelom
b. Blastocoel
c. Archenteron
d. Chorion

Answer 1

Hint: In embryonic development, the zygote is formed by the fertilization of sperm and egg, and the zygote is diploid in nature where it undergoes rapid divisions, and at the blastocyst stage it is attached to the endometrial wall of the uterus.

Complete answer:
- After the formation of the zygote, cell division takes place, where on the second day it has two cells, and third, it has 4 cells. By the 5th day, it obtained the 16 cell stage called a morula.
- This morula by the 7th day it reaches the blastula stage, where it is present as solid cell mass, and differentiation of cells happens.
- The cells are tightly compacted with each other and the outer layer cells form into trophoblast, and some cells inside form the inner cell mass, inside some cells disintegrates and fluid accumulates and appears as blastocoel.
- The inner cell mass is also called embryoblast, develops into a future embryo, while the outer layer trophoblast develops into the placenta in the future.
- The blastocyst stage forms one week after fertilization, and it occurs in the uterus.
- Later it implants into the endometrium uterine wall, with the help of a trophoblast.and later, germs layers form in the embryo, where the process of conversion of bilaminar to trilaminar is called gastrulation.
- The layers formed in the gastrulation are ectoderm, endoderm, and mesoderm, and the cavity of the gastrula is called archenteron.
- When it comes to the other options, Coelom is the fluid-filled cavity, where the blastocoel is the cavity of a blastocyst, and the chorion is formed by extraembryonic mesoderm.

Hence, the correct answer is option (C).

Note: After the blastocyst stage, the embryonic stage starts to begin, where all the internal organs and features, start to develop, and the heart, brain, spinal cord start to appear and visible in this age, after 3 months, it is called a fetus.